C++的MYDll.dll中定义了

TCHAR* GetInfo  (void)

在C#中引用

class CardRead
        {

[DllImport("MYDll.dll")]
            public static extern IntPtr GetInfo();

}

程序中调用

IntPtr Inf = CardRead.GetInfo();//调用
string Infstr = Marshal.PtrToStringAuto(Inf);//转字符串

c#调用C++时处理tchar *转字符串